> -----Original Message----- > From: Zev Weiss <zev@xxxxxxxxxxxxxxxxx> > Sent: Wednesday, December 23, 2020 11:54 AM > To: Ryan Chen <ryan_chen@xxxxxxxxxxxxxx> > Cc: Joel Stanley <joel@xxxxxxxxx>; Eddie James <eajames@xxxxxxxxxxxxx>; > Mauro Carvalho Chehab <mchehab@xxxxxxxxxx>; Andrew Jeffery > <andrew@xxxxxxxx>; linux-media@xxxxxxxxxxxxxxx; OpenBMC Maillist > <openbmc@xxxxxxxxxxxxxxxx>; Linux ARM > <linux-arm-kernel@xxxxxxxxxxxxxxxxxxx>; linux-aspeed > <linux-aspeed@xxxxxxxxxxxxxxxx>; Linux Kernel Mailing List > <linux-kernel@xxxxxxxxxxxxxxx>; Jae Hyun Yoo <jae.hyun.yoo@xxxxxxxxxxxxxxx> > Subject: Re: [PATCH 2/3] aspeed-video: clear spurious interrupt bits > unconditionally > > On Tue, Dec 22, 2020 at 08:53:33PM CST, Ryan Chen wrote: > >> -----Original Message----- > >> From: Joel Stanley <joel@xxxxxxxxx> > >> Sent: Wednesday, December 23, 2020 9:07 AM > >> To: Zev Weiss <zev@xxxxxxxxxxxxxxxxx>; Ryan Chen > >> <ryan_chen@xxxxxxxxxxxxxx> > >> Cc: Eddie James <eajames@xxxxxxxxxxxxx>; Mauro Carvalho Chehab > >> <mchehab@xxxxxxxxxx>; Andrew Jeffery <andrew@xxxxxxxx>; > >> linux-media@xxxxxxxxxxxxxxx; OpenBMC Maillist > >> <openbmc@xxxxxxxxxxxxxxxx>; Linux ARM > >> <linux-arm-kernel@xxxxxxxxxxxxxxxxxxx>; linux-aspeed > >> <linux-aspeed@xxxxxxxxxxxxxxxx>; Linux Kernel Mailing List > >> <linux-kernel@xxxxxxxxxxxxxxx>; Jae Hyun Yoo > >> <jae.hyun.yoo@xxxxxxxxxxxxxxx> > >> Subject: Re: [PATCH 2/3] aspeed-video: clear spurious interrupt bits > >> unconditionally > >> > >> On Tue, 22 Dec 2020 at 19:14, Zev Weiss <zev@xxxxxxxxxxxxxxxxx> wrote: > >> > > >> > On Mon, Dec 21, 2020 at 10:47:37PM CST, Joel Stanley wrote: > >> > >On Tue, 15 Dec 2020 at 02:46, Zev Weiss <zev@xxxxxxxxxxxxxxxxx> > wrote: > >> > >> > >> > >> Instead of testing and conditionally clearing them one by one, > >> > >> we can instead just unconditionally clear them all at once. > >> > >> > >> > >> Signed-off-by: Zev Weiss <zev@xxxxxxxxxxxxxxxxx> > >> > > > >> > >I had a poke at the assembly and it looks like GCC is clearing the > >> > >bits unconditionally anyway, so removing the tests provides no change. > >> > > > >> > >Combining them is a good further optimization. > >> > > > >> > >Reviewed-by: Joel Stanley <joel@xxxxxxxxx> > >> > > > >> > >A question unrelated to this patch: Do you know why the driver > >> > >doesn't clear the status bits in the interrupt handler? I would > >> > >expect it to write the value of sts back to the register to ack > >> > >the pending interrupt. > >> > > > >> > > >> > No, I don't, and I was sort of wondering the same thing actually -- > >> > I'm not deeply familiar with this hardware or driver though, so I > >> > was a bit hesitant to start messing with things. (Though maybe > >> > doing so would address the "stickiness" aspect when it does > >> > manifest.) Perhaps Eddie or Jae can shed some light here? > >> > >> I think you're onto something here - this would be why the status > >> bits seem to stick until the device is reset. > >> > >> Until Aspeed can clarify if this is a hardware or software issue, I > >> suggest we ack the bits and log a message when we see them, instead > >> of always ignoring them without taking any action. > >> > >> Can you write a patch that changes the interrupt handler to ack > >> status bits as it handles each of them? > >> > >Hello Zev, before the patch, do you met issue with irq handler? > >[continuous incoming?] > > > >In aspeed_video_irq handler should only handle enable interrupt expected. > > u32 sts = aspeed_video_read(video, VE_INTERRUPT_STATUS); > > + sts &= aspeed_video_read(video, VE_INTERRUPT_CTRL); > > > >Ryan > > > > Hi Ryan, > > Prior to any of these patches I encountered a problem pretty much exactly like > what Jae described in his commit message in 65d270acb2d (but the kernel I > was running included that patch). Adding the diagnostic in patch #1 of this > series showed that it was apparently the same problem, just with a different > interrupt that Jae's patch didn't include. > > From what you wrote above, I gather that it is in fact expected for the > hardware to assert interrupts that aren't enabled in VE_INTERRUPT_CTRL? > If so, I guess something like that would obviate the need for both Jae's earlier > patch and this whole series. > Yes, I expected handle enabled in VE_INTERRUPT_CTRL. > I think the question Joel raised is somewhat independent though -- if the > VE_INTERRUPT_STATUS register asserts interrupts we're not actually using, > should the driver acknowledge them anyway or just leave them alone? My opinion will keep them alone, ignore them. > (Though if we're just going to ignore them anyway maybe it doesn't ultimately > matter very much.) > > > Zev
